Since ikiwiki uses open :utf8, perl assumes that files contain valid utf-8.
If it turns out to be malformed it may later crash while processing strings
read from them, with 'Malformed UTF-8 character (fatal)'.
As at least a quick fix, use utf8::valid as soon as data is read, and if
it's not valid, call encode_utf8 on the string, thus clearing the utf-8
flag. This may cause follow-on encoding problems, but will avoid this
crash, and the input file was broken anyway, so GIGO is a reasonable
response. (I looked at calling decode_utf8 after, but it seemed to cause
more trouble than it was worth. BTW, use open ':encoding(utf8)' avaoids
this problem, but the corrupted data later causes Storable to crash when
writing the index.)
This is a quick fix, clearly imperfect:
- It might be better to explicitly call decode_utf8 when reading files,
rather than using the IO layer.
- Data read other than by readfile() can still sneak in bad utf-8. While
ikiwiki does very little file input not using it, stdin for the CGI
would be one way.
The fix involved embedding the session id in the forms, and not allowing the
forms to be submitted if the embedded id does not match the session id.
In the case of the preferences form, if the session id is not embedded,
then the CGI parameters are cleared. This avoids a secondary attack where the
link to the preferences form prefills password or other fields, and
the user hits "submit" without noticing these prefilled values.
In the case of the editpage form, the anonok plugin can allow anyone to edit,
and so I chose not to guard against CSRF attacks against users who are not
logged in. Otherwise, it also embeds the session id and checks it.
For page editing, I assume that the user will notice if content or commit
message is changed because of CGI parameters, and won't blndly hit save page.
So I didn't block those CGI paramters. (It's even possible to use those CGI
parameters, for good, not for evil, I guess..)
The only other CSRF attack I can think of in ikiwiki involves the poll plugin.
It's certianly possible to set up a link that causes the user to unknowingly
vote in a poll. However, the poll plugin is not intended to be used for things
that people would want to attack, since anyone can after all edit the poll page
and fill in any values they like. So this "attack" is ignorable.
plugins's support for inserting html link and meta tags. Now such content
is passed through the htmlscrubber like everything else.
* Unfortunatly, that means that some valid uses of those tags are no longer
usable, and special case methods needed to be added for including
stylesheets, and for doing openid delegation. If you use either of these
in your wiki, it will need to be modified. See the meta plugin docs
for details.
cookies to only be sent over ssl connections to avoid interception.
* Factor out the cgi header printing code into a new function.
* Fix preferences page on anonok wikis; still need to sign in to get
to the preferences page.
text blocks, for easy nesting of quotes inside.
* Add a template plugin.
* Use the template plugin to add infoboxes to each plugin page listing basic
info about the plugin.
* Added a pagecount plugin, enabled by default.
* Support PreProcessorDirectives with no parameters, ie "[[pagecount ]]".
* Fixed/optimised backlinks code, to avoid rebuilding pages to update
backlinks when the backlinks hadn't really changed.
* Moved inline page support, rss generation etc into the inline plugin,
enabled by default.
* Added brokenlinks plugin, not enabled by default, but rather handy.
* Fix several broken links in the doc wiki.
Joey Hess
Simon McVittie
Joey Hess
joey
www-data